void
handle_ether(const u_char * pkt, int len, void *userdata)
{
struct ether_header *e = (struct ether_header *)pkt;
unsigned short etype;
if (len < ETHER_HDR_LEN)
return;
etype = nptohs(&e->ether_type);
if (callback_ether)
if (0 != callback_ether(pkt, len, userdata))
return;
pkt += ETHER_HDR_LEN;
len -= ETHER_HDR_LEN;
if (ETHERTYPE_8021Q == etype) {
unsigned short vlan = nptohs((unsigned short *) pkt);
if (callback_vlan)
if (0 != callback_vlan(vlan, userdata))
return;
etype = nptohs((unsigned short *)(pkt + 2));
pkt += 4;
len -= 4;
}
if (len < 0)
return;
/* fprintf(stderr, "Ethernet packet of len %d ethertype %#04x\n", len, etype); */
if (is_ethertype_ip(etype)) {
handle_ip((struct ip *)pkt, len, userdata);
}
}
void
handle_ppp(const u_char * pkt, int len, void *userdata)
{
char buf[PCAP_SNAPLEN];
unsigned short proto;
if (len < 2)
return NULL;
if (*pkt == PPP_ADDRESS_VAL && *(pkt + 1) == PPP_CONTROL_VAL) {
pkt += 2; /* ACFC not used */
len -= 2;
}
if (len < 2)
return NULL;
if (*pkt % 2) {
proto = *pkt; /* PFC is used */
pkt++;
len--;
} else {
proto = nptohs(pkt);
pkt += 2;
len -= 2;
}
if (is_ethertype_ip(proto))
handle_ip((struct ip *)pkt, len, userdata);
}
void
handle_linux_sll(const u_char * pkt, int len, void *userdata)
{
struct sll_header *s = (struct sll_header *)pkt;
unsigned short etype, eproto;
if (len < SLL_HDR_LEN)
return;
etype = nptohs(&s->sll_pkttype);
if (etype == LINUX_SLL_BROADCAST || etype == LINUX_SLL_MULTICAST)
return;
eproto = nptohs(&s->sll_protocol);
if (eproto != ETHERTYPE_IP)
return;
pkt += SLL_HDR_LEN;
len -= SLL_HDR_LEN;
/* fprintf(stderr, "linnux cooked packet of len %d type %#04x proto %#04x\n", len, etype, eproto); */
handle_ip((struct ip *)pkt, len, userdata);
}
void
handle_gre(const u_char * gre, int len, void *userdata)
{
int grelen = 4;
unsigned short flags = nptohs(gre);
unsigned short etype = nptohs(gre + 2);
if (len < grelen)
return;
if (callback_gre)
callback_gre(gre, len, userdata);
if (flags & 0x0001) /* checksum present? */
grelen += 4;
if (flags & 0x0004) /* key present? */
grelen += 4;
if (flags & 0x0008) /* sequence number present? */
grelen += 4;
if (is_ethertype_ip(etype))
handle_ip((struct ip *) (gre + grelen), len - grelen, userdata);
}
static off_t
grok_additional_for_opt_rr(const u_char *buf, int len, off_t offset, dns_message * m)
{
int x;
unsigned short sometype;
unsigned short someclass;
unsigned short us;
char somename[MAX_QNAME_SZ];
x = rfc1035NameUnpack(buf, len, &offset, somename, MAX_QNAME_SZ);
if (0 != x)
return 0;
if (offset + 10 > len)
return 0;
sometype = nptohs(buf + offset);
someclass = nptohs(buf + offset + 2);
if (sometype == T_OPT) {
m->edns.found = 1;
m->edns.bufsiz = someclass;
memcpy(&m->edns.version, buf + offset + 5, 1);
us = nptohs(buf + offset + 6);
m->edns.DO = (us >> 15) & 0x01; /* RFC 3225 */
}
static off_t
grok_question(const u_char *buf, int len, off_t offset, char *qname, unsigned short *qtype, unsigned short *qclass)
{
char *t;
int x;
x = rfc1035NameUnpack(buf, len, &offset, qname, MAX_QNAME_SZ);
if (0 != x)
return 0;
if ('\0' == *qname)
strcpy(qname, ".");
/* XXX remove special characters from QNAME */
while ((t = strchr(qname, '\n')))
*t = ' ';
while ((t = strchr(qname, '\r')))
*t = ' ';
for (t = qname; *t; t++)
*t = tolower(*t);
if (offset + 4 > len)
return 0;
*qtype = nptohs(buf + offset);
*qclass = nptohs(buf + offset + 2);
offset += 4;
return offset;
}
/*
* When passing on to the next layers, use the ip_len
* value for the length, unless the given len happens to
* to be less for some reason. Note that ip_len might
* be less than len due to Ethernet padding.
*/
void
handle_ipv4(const struct ip *ip, int len, void *userdata)
{
int offset;
int iplen;
uint16_t ip_off;
if (len < sizeof(*ip))
return;
offset = ip->ip_hl << 2;
iplen = XMIN(nptohs(&ip->ip_len), len);
if (callback_ipv4)
if (0 != callback_ipv4(ip, iplen, userdata))
return;
ip_off = ntohs(ip->ip_off);
if ((ip_off & (IP_OFFMASK | IP_MF)) && _reassemble_fragments) {
handle_ipv4_fragment(ip, iplen, userdata);
} else if (IPPROTO_UDP == ip->ip_p) {
handle_udp((struct udphdr *)((char *)ip + offset), iplen - offset, userdata);
} else if (IPPROTO_TCP == ip->ip_p) {
handle_tcp((struct tcphdr *)((char *)ip + offset), iplen - offset, userdata);
} else if (IPPROTO_GRE == ip->ip_p) {
handle_gre((u_char *)ip + offset, iplen - offset, userdata);
}
}
static int
rfc1035NameUnpack(const u_char *buf, size_t sz, off_t * off, char *name, int ns)
{
off_t no = 0;
unsigned char c;
size_t len;
static int loop_detect = 0;
if (loop_detect > 2)
return 4; /* compression loop */
if (ns <= 0)
return 4; /* probably compression loop */
do {
if ((*off) >= sz)
break;
c = *(buf + (*off));
if (c > 191) {
/* blasted compression */
int rc;
unsigned short s;
off_t ptr;
s = nptohs(buf + (*off));
(*off) += sizeof(s);
/* Sanity check */
if ((*off) >= sz)
return 1; /* message too short */
ptr = s & 0x3FFF;
/* Make sure the pointer is inside this message */
if (ptr >= sz)
return 2; /* bad compression ptr */
if (ptr < DNS_MSG_HDR_SZ)
return 2; /* bad compression ptr */
loop_detect++;
rc = rfc1035NameUnpack(buf, sz, &ptr, name + no, ns - no);
loop_detect--;
return rc;
} else if (c > RFC1035_MAXLABELSZ) {
/*
* "(The 10 and 01 combinations are reserved for future use.)"
*/
return 3; /* reserved label/compression flags */
break;
} else {
(*off)++;
len = (size_t) c;
if (len == 0)
break;
if (len > (ns - 1))
len = ns - 1;
if ((*off) + len > sz)
return 4; /* message is too short */
if (no + len + 1 > ns)
return 5; /* qname would overflow name buffer */
memcpy(name + no, buf + (*off), len);
(*off) += len;
no += len;
*(name + (no++)) = '.';
}
} while (c > 0);
if (no > 0)
*(name + no - 1) = '\0';
/* make sure we didn't allow someone to overflow the name buffer */
assert(no <= ns);
return 0;
}
x = rfc1035NameUnpack(buf, len, &offset, somename, MAX_QNAME_SZ);
if (0 != x)
return 0;
if (offset + 10 > len)
return 0;
sometype = nptohs(buf + offset);
someclass = nptohs(buf + offset + 2);
if (sometype == T_OPT) {
m->edns.found = 1;
m->edns.bufsiz = someclass;
memcpy(&m->edns.version, buf + offset + 5, 1);
us = nptohs(buf + offset + 6);
m->edns.DO = (us >> 15) & 0x01; /* RFC 3225 */
}
/* get rdlength */
us = nptohs(buf + offset + 8);
offset += 10;
if (offset + us > len)
return 0;
offset += us;
return offset;
}
void
handle_dns(const u_char *buf, uint16_t len, transport_message *tm, DMC *dns_message_callback)
{
unsigned short us;
off_t offset;
int qdcount;
int ancount;
int nscount;
void
handle_ipv6(const struct ip6_hdr *ip6, int len, void *userdata)
{
int offset;
int nexthdr;
uint16_t payload_len;
if (len < sizeof(*ip6))
return;
if (callback_ipv6)
if (0 != callback_ipv6(ip6, len, userdata))
return;
offset = sizeof(struct ip6_hdr);
nexthdr = ip6->ip6_nxt;
payload_len = nptohs(&ip6->ip6_plen);
/*
* Parse extension headers. This only handles the standard headers, as
* defined in RFC 2460, correctly. Fragments are discarded.
*/
while ((IPPROTO_ROUTING == nexthdr) /* routing header */
||(IPPROTO_HOPOPTS == nexthdr) /* Hop-by-Hop options. */
||(IPPROTO_FRAGMENT == nexthdr) /* fragmentation header. */
||(IPPROTO_DSTOPTS == nexthdr) /* destination options. */
||(IPPROTO_AH == nexthdr) /* authentication header. */
||(IPPROTO_ESP == nexthdr)) { /* encapsulating security payload. */
typedef struct {
uint8_t nexthdr;
uint8_t length;
} ext_hdr_t;
ext_hdr_t *ext_hdr;
uint16_t ext_hdr_len;
/* Catch broken packets */
if ((offset + sizeof(ext_hdr)) > len)
return;
/* Cannot handle fragments. */
if (IPPROTO_FRAGMENT == nexthdr)
return;
ext_hdr = (ext_hdr_t *) ((char *)ip6 + offset);
nexthdr = ext_hdr->nexthdr;
ext_hdr_len = (8 * (ext_hdr->length + 1));
/* This header is longer than the packets payload.. WTF? */
if (ext_hdr_len > payload_len)
return;
offset += ext_hdr_len;
payload_len -= ext_hdr_len;
} /* while */
/* Catch broken and empty packets */
if (((offset + payload_len) > len)
|| (payload_len == 0)
|| (payload_len > PCAP_SNAPLEN))
return;
if (IPPROTO_UDP == nexthdr) {
handle_udp((struct udphdr *)((char *)ip6 + offset), payload_len, userdata);
} else if (IPPROTO_TCP == nexthdr) {
handle_tcp((struct tcphdr *)((char *)ip6 + offset), payload_len, userdata);
} else if (IPPROTO_GRE == nexthdr) {
handle_gre((u_char *)ip6 + offset, payload_len, userdata);
}
}
